An electric motor usually comprises a movable rotor which is surrounded by a stationary stator. The rotor may include a permanent magnet and the stator may include a plurality of coils, for example, three coils wick are driven by timely shifter alternating voltages as exciting voltages to generate a rotational magnetic field around the stator. The rotational magnetic field generates a moment of force at the permanently excited rotor. In order to enable a continuous rotational movement of the rotor, the rotational magnetic field has to be commutated at defined times in dependence on the current position of the rotor in the rotational magnetic field or in dependence on the current direction of the magnetic field of the permanent magnet of the rotor in the rotational field generated by the stator.
In applications with BLDC motors, the commutation of the rotational magnetic field is accomplished in dependence on the current position of the rotor in the rotational magnetic field of the coils of the stator, the revolution speed of the rotor and the motor torque. In order to detect the position of the rotor in the rotational magnetic field of the coils of the stator, the electric motor may comprise a motor position sensor device. The motor position sensor device may be formed as a chip which may be mounted on the movable rotor. The motor position sensor device may comprise a magnetic field detection sensor to detect the position of the rotor in relation to the arrangement of the coils of the stator. The motor position sensor device may transfer the detected position of the rotor to a motor control driver device coupled to the motor. The motor control driver device comprises a motor controller circuit to control the generation of the exciting alternating current voltages for applying to the coils of the stator to generate the rotational magnetic field.
The motor position sensor device has to be supplied by a supply voltage to operate the motor position sensor in an operation mode to detect the position of the rotor relative to the coils of the stator. Safety critical motor applications, for example safety critical BLDC motor applications, need to detect a disruption on the supply line to provide the supply voltage or any other failure in providing the supply voltage to guarantee a proper function of the motor.
It is desirable to provide a motor position sensor device which enables a reliable operation of the motor position sensor device in case of a disruption of a supply voltage of the motor position sensor device. A further concern is to provide an electric motor which enables a reliable operation of the electric motor in case of a disruption of a supply voltage of a motor position sensor device of the electric motor. A further need is to provide an electric system to provide a supply voltage to a motor position sensor device of an electric motor which enables a reliable operation of the motor position sensor device in case of a disruption of the supply voltage of the motor position sensor device. Another concern is to provide an electric arrangement to control an electric motor such that a proper function of the electric motor is ensured in case of a disruption of a supply voltage of a motor position sensor device of the electric motor to detect a position of the motor.